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      <title>设计模式与架构设计 - 交互式测验</title>
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        .option-item:hover {
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        .option-item.selected {
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          padding: 20px 30px;
          display: flex;
          justify-content: space-between; /* 将按钮分布在两侧 */
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          min-height: 65px; /* Reserve space */
        }

        .nav-btn {
          background-color: #4a90e2;
          color: white;
          border: none;
          border-radius: 8px;
          padding: 10px 20px;
          font-size: 16px;
          font-weight: 500;
          cursor: pointer;
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          box-shadow: 0 4px 12px rgba(0,0,0,0.15);
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            gap: 20px;
            margin-bottom: 40px;
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            border-radius: 12px;
            padding: 20px;
            width: 180px;
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      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>设计模式与架构设计 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "在文档「2.1 单例模式」的双重检查锁（Double-Checked Locking）实现中，`volatile` 关键字扮演了什么关键角色？",
    "options": [
      "锁定 `Singleton.class` 对象，防止多个线程同时进入同步块。",
      "防止指令重排序，确保多线程环境下的内存可见性。",
      "告诉垃圾回收器不要回收 `instance` 对象。",
      "确保 `instance` 变量的所有操作都具有原子性。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "`volatile` 关键字在此处的关键作用是确保对 `instance` 变量的写操作对所有线程立即可见，并且禁止了指令重排序优化。如果没有 `volatile`，一个线程可能会读到一个未被完全初始化的 `instance` 对象（因为`instance = new Singleton()`并非原子操作），从而导致程序错误。",
    "source": "文档中「2.1 单例模式（Singleton Pattern）」部分",
    "hint": "文档中提到，该关键字确保了“多线程环境下的内存可见性”。"
  },
  {
    "question": "根据文档，在实现生产者-消费者模式时，推荐使用哪种 Java 工具来简化线程同步和队列管理？",
    "options": [
      "`java.util.concurrent.atomic.AtomicInteger`",
      "`java.util.Observer` 接口",
      "`java.util.concurrent.BlockingQueue`",
      "`java.util.ArrayList` 配合 `synchronized` 关键字手动管理"
    ],
    "correctAnswerIndex": 2,
    "explanation": "`BlockingQueue` 是一个线程安全的队列，它为生产者-消费者场景提供了内置的阻塞功能。当队列满时，尝试放入元素的生产者线程会被阻塞；当队列空时，尝试取出元素的消费者线程会被阻塞。这极大地简化了开发者需要处理的同步逻辑。",
    "source": "文档中「2.2 生产者-消费者模式（Producer-Consumer Pattern）」部分",
    "hint": "文档中提到一种已经封装了线程同步和队列管理的类，能够有效处理队列为空或满的情况。"
  },
  {
    "question": "文档中提到的线程池模式（Thread Pool Pattern）最主要的设计目的是什么？",
    "options": [
      "通过复用线程，避免频繁创建和销毁线程带来的性能开销。",
      "为每个任务创建一个独立的线程以实现完全隔离。",
      "保证所有任务按照提交的先后顺序严格执行。",
      "自动解决多线程中的死锁问题。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "线程的创建和销毁是相对昂贵的操作。线程池模式通过维护一组预先创建好的工作线程，并将任务提交给这些线程来执行，实现了线程的复用。这显著减少了系统开销，提高了任务处理的响应速度和整体资源利用率。",
    "source": "文档中「2.4 线程池模式（Thread Pool Pattern）」部分",
    "hint": "思考一下，如果每次来一个新任务都创建一个新线程，会带来什么性能问题？线程池正是为了解决这个问题。"
  },
  {
    "question": "在「3.1 线程安全的设计」一节中，提到了多种保证线程安全的机制。以下哪一种属于“无锁编程”的范畴？",
    "options": [
      "使用 `ReentrantLock` 对临界区代码加锁。",
      "使用 `AtomicInteger` 进行原子操作。",
      "使用线程局部存储（Thread Local Storage）。",
      "使用 `synchronized` 关键字修饰方法。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "无锁编程旨在通过不使用传统互斥锁（如 `synchronized` 或 `ReentrantLock`）的方式来保证线程安全，从而避免锁竞争带来的性能开销和死锁风险。`AtomicInteger` 内部使用了 CAS（Compare-And-Swap）这样的硬件级别原子指令来实现无锁的线程安全更新。",
    "source": "文档中「3.1 线程安全的设计」部分",
    "hint": "文档将保证线程安全的策略分为了几类，其中一类是避免使用锁来提高性能。"
  },
  {
    "question": "根据文档对事件驱动架构（EDA）的描述，它在处理大规模并发应用时的主要优势是什么？",
    "options": [
      "减少了应用程序的内存占用。",
      "强制所有操作都同步执行，保证了数据强一致性。",
      "简化了代码逻辑，使得程序更容易调试。",
      "通过事件的发布和订阅实现高度解耦，避免阻塞等待。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "事件驱动架构的核心思想是组件之间不直接调用，而是通过发布和订阅事件进行通信。这使得组件之间高度解耦，一个组件的变更或失败不会直接影响其他组件。同时，事件处理通常是异步的，这避免了因等待某个操作完成而产生的阻塞，从而提升了系统的并发处理能力和整体吞吐量。",
    "source": "文档中「3.3 事件驱动架构（EDA）」部分",
    "hint": "文档中提到该架构是一种“高度解耦的设计模式”，并强调其可以避免某种性能瓶颈。"
  },
  {
    "question": "假设一个多线程系统需要处理多种任务，其中一些是高优先级的紧急任务（如交易处理），另一些是低优先级的常规任务（如日志记录）。根据「3.4 任务调度与队列管理」的描述，哪种任务调度策略最适合这个场景？",
    "options": [
      "延迟队列",
      "FIFO（先进先出）队列",
      "线程局部存储（TLS）",
      "优先级队列"
    ],
    "correctAnswerIndex": 3,
    "explanation": "优先级队列允许为进入队列的任务分配一个优先级。调度器（如线程池）会优先从队列中取出并执行优先级最高的任务。这确保了紧急和重要的任务能够被及时处理，即使队列中已经堆积了大量的低优先级任务。",
    "source": "文档中「3.4 任务调度与队列管理」部分",
    "hint": "文档中介绍了一种专门用于处理“任务优先级不同的场景”的队列策略。"
  },
  {
    "question": "文档在「1.2 并发编程面临的挑战」中提到了死锁问题。死锁的典型特征是什么？",
    "options": [
      "单个线程因等待一个永远不会发生的事件而被无限期阻塞。",
      "多个线程因相互持有对方需要的资源而进入互相等待的状态。",
      "由于线程频繁切换，导致CPU大量时间消耗在上下文切换上。",
      "多个线程同时修改共享数据，导致数据最终状态不可预测。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "死锁的定义是：一组进程（或线程）中，每个进程都在等待一个只有该组中其他进程才能释放的资源。这种相互等待导致所有参与的进程都无法继续执行，从而使系统陷入停滞状态。这是并发编程中一个非常经典且棘手的问题。",
    "source": "文档中「1.2 并发编程面临的挑战」部分",
    "hint": "该问题的核心在于“相互依赖”和“互相等待”。"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
        // 存储每个问题的回答状态
        const userAnswers = new Array(quizData.length).fill(null); 

        const questionTextEl = document.getElementById('question-text');
        const optionsListEl = document.getElementById('options-list');
        const resultContainerEl = document.getElementById('result-container');
        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

        function loadQuestion() {
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          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
          if (currentQuestionIndex >= quizData.length) {
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            return;
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          questionTextEl.textContent = `(${currentQuestionIndex + 1}/${quizData.length}) ${currentQuestion.question}`;
          
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            li.className = 'option-item';
            li.textContent = optionText;
            li.dataset.index = index; // Store index in a data attribute
            // 如果这道题已经回答过，恢复状态
            if (userAnswers[currentQuestionIndex] !== null) {
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                    li.classList.add('selected');
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          // 如果已经回答过，直接显示结果
          if (userAnswers[currentQuestionIndex] !== null) {
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          updateNavigationButtons();
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        }

        function selectOption(optionIndex) {
            userAnswers[currentQuestionIndex] = optionIndex;
            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
                return answer === quizData[index].correctAnswerIndex ? acc + 1 : acc;
            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
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            const answeredQuestions = userAnswers.filter(answer => answer !== null).length;
            const progressPercentage = (answeredQuestions / quizData.length) * 100;
            progressIndicatorEl.style.width = `${progressPercentage}%`;
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            prevBtn.style.display = 'block';
            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
            if (!quizData[currentQuestionIndex].hint) {
                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
            } else {
                hintBtn.disabled = false;
            }
        }

        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
            Array.from(optionsListEl.children).forEach((child, index) => {
                child.style.pointerEvents = 'none';
                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
                }
            });
        }

        function goToNextQuestion() {
            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
        }

        function goToPreviousQuestion() {
            if (currentQuestionIndex > 0) {
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                loadQuestion();
            }
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        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  